COMMAND

SYNOPSIS

DESCRIPTION

The
urrhythm
command outputs a single Humdrum spine (**URrhythm) containing data
representing rhythmic `prototypes' (Ur-rhythms) evident in a musical passage.
The command implements a variation of Johnson-Laird's theory of rhythmic
prototypes (see REFERENCES below).
In order to identify the rhythmic prototypes,
urrhythm
requires information about note onsets and metric position.
These may be provided via two input spines:
**kern (or **recip) and **metpos.

Johnson-Laird's rhythmic-prototype theory can be applied only to musical
passages conforming to some established metric context,
such as 2/4, 3/2, or 12/8 meters.
The
urrhythm
command handles all regular types of meters (simple and compound,
duple, triple and quadruple).
Specifically, any meter having a "numerator"
of 2, 3, 4, 6, 9, or 12 can be processed.
Urrhym
adapts to changes of meter, but is unable to handle irregular meters.
If an irregular meter is encountered in the input an error is generated
and the command terminates.

urrhythm
characterizes each beat in a passage as belonging to one of
three beat types:
Note
(N),
Syncopation
(S), or
Other
(O).
Only major beats are characterized in this way.
Hence, in 3/4 or 9/8 meters, three beats will be characterized for
each complete measure.
Similarly, in 4/2 and 12/16, four beats will be characterized for
each complete measure.

A "Note" (signified in the output by the letter `N') is defined as a beat
that coincides with a note onset.

A "Syncopation" (signified by the letter `S') is defined as arising
when no note-onset happens on a beat whose position in the metric
hierarchy is greater than that of the most recent note onset.
By way of example, imagine a measure in 4/4 meter containing a quarter-note,
followed by a half-note, followed by a quarter-note.
The third beat position does not coincide with a note onset.
The most recent note onset prior to the third beat occurs on beat two.
Since beat three is a more important metric position than beat two,
beat three is deemed to be syncopated.

Syncopated beats can happen only after the first note onset;
subsequent syncopated moments will require another note onset
(i.e. two syncopated moments can't occur in a row without some note
onset intervening).

An "Other" (signified by the letter `O') is any beat that is not
a Note (N) or a syncopation (S).

It is recommended that output files produced using the
urrhythm
command should be given names with the distinguishing `.urr' extension.

OPTIONS

The
urrhythm
command provides only a help option:

-h

displays a help screen summarizing the command syntax

Options are specified in the command line.

EXAMPLES

The following example illustrates the operation of
urrhythm.
The first two spines (**kern and **metpos)
constitute the input.
The third spine (**URrhythm) is added by the
urrhythm
command.
All three spines are given in the output.

**kern

**metpos

**URrhythm

*M4/4

*M4/4

*M4/4

*tb8

*tb8

*tb8

8g

3

N

8g#

4

.

8a

2

N

[8cc

4

.

8cc]

3

S

8a

4

.

=1

=1

=1

4.cc

1

N

.

4

.

.

3

O

[8b-

4

.

4.b-]

2

S

.

4

.

.

3

O

[8g

4

.

=2

=2

=2

8g]

1

S

[8e-

4

.

8e-]

3

S

4.r

4

.

.

2

O

.

4

.

[4c

3

N

.

4

.

=3

=3

=3

2c]

1

S

.

4

.

.

3

O

.

4

.

4r

2

O

.

4

.

*-

*-

*-

WARNINGS

The
urrhythm
command is currently unable to handle Humdrum spine-path changes
-- such as join-path, exchange-path, or split-path.
If spine-path changes are encountered an error is issued and the
command terminates.

SEE ALSO

NOTE

The
urrhythm
command differs from Johnson-Laird's theory in the
definition of syncopation.
Johnson-Laird's theory requires that a listener be able to
identify a syncopation retrospectively.
That is, a listener is able to determine whether the current
beat is a syncopation, only by determining what happens at the beginning
of the next beat.
The algorithm used here avoids the theoretical assumption of backward listening.
(See
Simpson & Huron, 1993.)